Sunday, March 23, 2014

Ultrasound Measurements in the First Trimester Are Not as Accurate As You Might Believe and Lead to Misdiagnosing Miscarriages!

I've talked to thousands of women since I shared my misdiagnosed blighted ovum story.  I am convinced that the first trimester ultrasound measurements are not as accurate as your doctor may have you believe.

Why do I believe this?  For a couple of reasons:

- I've had women tell me they've had ultrasounds done the same day by two different techs and the measurements are quite different.  Please remember, this is a person doing the measuring using the equipment.  It is subject to human error and interpretation.

- Quite a few women now have known the exact day of conception; They've had no doubt.  Yet, the ultrasound measurements are one to two weeks behind.  This happened with me as well. 

So, until recently, women would ask for any research to take to their doctors and until recently, there has been done.  We've collected story after story after story but some doctors like to put their faith in research and not real life experience.

I would like to direct you to a WebMD article that perhaps your doctor might take a bit more seriously:

Does ultrasound sometimes misdiagnose miscarriage?

Take the time to read it if you believe your doctor may be diagnosing you a bit too quickly based on ultrasound measurements.

In a nutshell, this article tells how there really are very few studies on ultrasound accuracy and are older studies as well. 

A newer study in the UK found that if a doctor diagnoses an impending miscarriage based on the fact that the gestational sac is 20mm with no baby, they are going to end up misdiagnosing some pregnancies.   Indeed, I had an ultrasound where the sac measured 21.5mm with no baby.   My doctor was a firm believer that the ultrasound guidelines were correct and really pressured me to end my pregnancy.  Fortunately, I refused...repeatedly! 

I can tell you what I also believe from the many women who have shared their stories:

- Doctors who do their own ultrasounds tend to make mistakes far more frequently than fully-trained ultrasound techs.  Techs have been through school to learn their trade.  Doctors go through a very short course.  They don't have anywhere near the same level of training with the equipment.

- More important than measurements is just seeing the baby or sac grow each week.  Of course, the article points out that even that isn't fullproof.  Human error.  One person's measurement is not always the same as another person's measurement.  That article points out the measurements sometimes vary by 8mm or more!  When you are looking for a growth of 1mm a day, 7mm a week, being off by eight mm can definitely lead to a misdiagnosis.

- The only true test of a blighted ovum is time.  I know waiting is torture.  I've been there.  I had to wait almost a month and fully expected to miscarry.  And, sadly, there are no guarantees.  Often a miscarriage diagnosis ends in miscarriage but, if there is even a slight chance, think of yourself a year down the road, will you look back and kick yourself for not waiting a couple extra weeks?

No matter what, always stay closely monitored and seek second (and third and fourth) opinions if you feel your doctor is diagnosing you too soon.



  1. Hi Kay, I conceived through IVF and at 6 weeks, the gestational sac and the heart beat was visualized. At 10 weeks (on March 26, 2014), after doing the U/S the doctor said that the fetal growth is slow and asked me to do a complete obstetric scan on April 1st. I didn't experience any pregnancy symptoms all these weeks except constipation. I had lots of hope that time, this is my third IVF; the first two had failed and I'm already 38. Do you think there is a chance that this pregnancy will continue?

  2. Hi Aparna. First of all (((hugs))). I am so sorry you have been going through so much. I don't believe first trimester ultrasounds are as accurate as they would like us to believe. Generally, it is advised that doctors wait a week after an ultrasound like this and recheck. Sounds as if your doctor is doing so (or close to a week in your case. I don't know how this will turn out but, please, keep us updated. (((Hugs)))

  3. Hi Kay, Thanks so much for responding to my earlier comment; it really made me feel good when I was feeling so low. BTW, I had cramps and bleeding on 31st March itself and the ultrasound scan showed that the growth had stopped. So I had a D & C. I'm completely numb; I'm not experiencing any emotions at all. I simply can't believe that this is happening to me! This is my second miscarriage. I had first conceived back in June 2012 through IUI only to have a miscarriage in October 2012. After that 2 IUI's and 2 IVF's had failed. I have mild PCOS but the doctor had said that the quality of my eggs were good. Considering my age and recurrent miscarriages and trouble with conceiving do you think I should try again with my own eggs or should I go for a donor egg?

    1. I am so very sorry for your loss. I know this must be especially difficult. You've been through so much (((hugs))) If they think your eggs are good, that's probably not the problem then. Take heart. I've talked to women who have had multiple miscarriages and they go on to carry a pregnancy to term. Praying for you!!!

    2. Hi Kay, thanks so much for your response. I've been advised to take 2 months rest. I'll just forget everything for a while and then decide about making a baby. You've been really very supportive! Hugs to you too!